9. Dennis Crowley, Jeff Glueck, Jon Steinback and Noah Weiss

CEO, COO, VP Product Experience, VP Product Management, Foursquare

In late 2013, Foursquare decided to roll the dice and relaunch its entire business. The result: Foursquare broke its check-in and venue-finding app into two separate products, Swarm and Foursquare.

Swarm houses the gamification elements the company was founded on; it allows users to check in to venues and find friends nearby. Foursquare is like a mobile-first version of Yelp, with food and activity recommendations and local search tools.

Crowley asked 11 Foursquare employees to oversee the rollout of the new products. Two employees, Noah Weiss and Jon Steinback, were named executives and helped manage the process along with Crowley and VP of Engineering, Harry Heyman. Steve Rosenblatt, Foursquare's head of sales, was in charge of managing advertisers and upcoming campaigns for the new Swarm and Foursquare apps.

In December 2013, the company raised $35 million in a Series D round from investors DFJ Growth and Smallcap World Fund. In February, Foursquare raised a $15 million in another Series D round, led by Microsoft. Glueck joined the company as COO over the summer.